docs: def feature_scp_generator(path):
          """ Return a generator over all feature matrices defined in a scp. """
  
          scp_entries = textfile.read_key_value_lines(path, separator=' ')
  
          for utterance_id, rx_specifier in scp_entries.items():
              yield utterance_id, KaldiWriter.read_float_matrix(rx_specifier)